For through the law I died to the law, so that I might live to God. I have been crucified with Christ; and it is no longer I who live, but it is Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me. I do not nullify the grace of God; for if justification comes through the law, then Christ died for nothing. Galatians 2:19-21, NRSVThese awkwardly translated words, even across several translations, make it clear that although there is a sense that Jesus died for our benefit, the believer also dies in some way. The believer is considered dead both to the law and to sin.
It's an odd phrase to use for someone who is plainly and biologically alive. Is this just a metaphor? As metaphor it's reduced to poetry; a nice word picture to convey the conversion experience. I think Paul isn't quite so vapid, however, and has deeper intentions. The very being of the believer has changed, and changed through death.
But what is that death? Today we'd refer to it as a transcendence of the self, but this doesn't do for Paul's purposes. It's not quite enough to just say that the believer has changed to the point that they're living as Christ would. Paul needs to connect this to torah and does so by linking torah and death. The ultimate consequence of torah is death, even though it was meant to bring life. And because death is an ultimate consequence, once a person is dead they are out of the scope of the law. They cannot be punished any more, neither can they be blessed any more. Along with Christ, Paul has died to the law and in so doing is free from the obligations of the law, free from the punishments of the law, and disqualified from claiming any benefits under that law.
If I died today, I would no longer have to pay taxes and would no longer be able to access benefits owed to me under Australian law. As dead to the law, I'm an invisible non-citizen; owing nothing and being owed nothing. Paul appears to put the believer in the same category. Invisible to the law, beyond its reach and beyond its protection. The believer has only the life of Christ.
The movement from death to life through participation in the death of Christ is therefore a qualitative difference in which the being of the believer is changed. No longer in the contract, now in the life of Christ. The death language is important because the believer has died, has transcended the self and transcended the law by escaping from it the only way possible. The self as we know it is utterly caught up in law, in the consequences of blessings and curses. The epistemological cause of sin is removed and replaced by the epistemological awareness of Christ.
The believer must die to the law in order to escape it. Without that death, without that crucifixion, the law still holds the believer.